A solar cell is a device capable of converting the energy of sunlight directly into electricity by the photovoltaic effect. Assemblies of cells are commonly used to make solar modules, also known as solar panels. The energy generated from these solar modules is an example of solar energy.
Solid-state photovoltaic cells are photosensitive diodes. When cells are exposed to light, photons elevate the energy of electrons within the diode material to a mobile state. Under proper electrical bias these free electrons flow from the diode to through the bias network, As a result, radiant energy is transformed to electrical energy.
Solar cells are often electrically connected and encapsulated as a module. Solar cells are also usually connected in series in modules, creating an additive voltage. Connecting cells in parallel will yield a higher current. Modules are then interconnected, in series or parallel, or both, to create an array with the desired peak DC voltage and current. Photovoltaic modules often have a sheet of glass on the front (sun up) side, allowing light to pass while protecting the photovoltaic cells from the elements (rain, hail, etc.).
To make practical use of the solar-generated energy, the electricity is often fed into the electricity grid using inverters (grid-connected photovoltaic power systems). In stand-alone power systems, batteries are used to store the energy for later access. In addition, solar panels can be used to power or recharge portable devices.